Study on the variable color and emissivity properties of Co doped TiO2 under temperature fluctuations

• Published in: Optical materials Vol. 85; pp. 254 - 260
• Main Authors: Xiang, Shanshan, Xu, Guoyue, Liu, Chuyang, Bu, Honghan, Zhang, Yanting
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2018
• Subjects: Band gap; Co doped TiO2 powders; Infrared emissivity; Thermochromism; Infrared emissivity; Band gap; Co doped TiO2 powders; Thermochromism
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2018.08.064

In this paper, Co doped TiO2 powders were prepared through solid-state reaction. The effects of sintering temperature on microstructures, morphologies, variable color and emissivity properties of the Co doped TiO2 powders were investigated in detail. The results show that Co2+ ions substitute for Ti4+ ions effectively in rutile TiO2 after heat-treating at 900 °C–1200 °C. Increasing sintering temperature from 900 °C to 1200 °C improves crystalline quality, substitution amount of Co2+ for Ti4+ and oxygen concentration of the Co doped TiO2 powders. All the Co doped TiO2 powders show reversible thermochromism, which are green at room temperature and yellow at testing temperature of ∼800 °C. Simultaneously, the maximum variation of infrared emissivity reaches to 0.332 with testing temperature changing from room temperature to 800 °C in the powders sintered at 1100 °C. The Co doped TiO2 powders are competitive materials for smart stealth compatible visible light and infrared wavebands. •The variable color and infrared emissivity of Co-doped TiO2 are reported for the first time.•The mechanisms for the variable color and emissivity under temperature fluctuations are fully revealed.•Reversible thermochromism and large emissivity variation of ∼0.332 are explored in the Co-doped TiO2 simultaneously.